<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>作用域链</title>
</head>

<body>
  <script>
    // ============================== 作用域链 ============================== 
    let a = 11
    let b = 22

    function f() {
      let a = 1
      function g() {
        a = 2
        console.log(a)  // ?
      }
      g()
    }

    f() 
  </script>
</body>

</html>